A turbine engine generally has several compressor stages, in particular a low-pressure (LP) compressor and a high-pressure (HP) compressor which belong to the main body of the engine. Upstream of the low-pressure compressor is arranged a movable-blade wheel of large dimensions, or fan, which feeds both the primary flow which passes through the LP and HP compressors and the cold flow, or secondary flow, which is directed directly towards a cold flow nozzle, referred to as a secondary nozzle. The fan is driven by the rotary shaft of the LP body and generally turns at the same speed as the shaft. However, it may be advantageous to make the fan turn at a rotational speed of less than that of the drive shaft or LP shaft, in particular when the fan has very large dimensions, for the purpose of adapting it better aerodynamically. For this purpose, a reduction gear is arranged between the LP shaft and a fan shaft which carries the fan.
Among the types of reduction gears used there are reduction gears having an epicyclic gear train, which have the advantage of offering considerable rates of reduction of the rotational speed, in a reduced space. These reduction gears are characterized by satellite type planet pinions which roll on an external ring gear and rotate about satellite axes borne by a planet carrier. For reasons of space required and weight, it is advantageous to make the satellites rotate on their shafts by means of hydrodynamic plain bearings. These bearings necessitate continuous lubrication, otherwise they deteriorate quickly, with all the consequences that this may have on the operation of the engine and the safety of the aircraft. Thus difficulties arise in terms of operational safety, and therefore it is necessary for precautionary measures to be taken against breakdown, such as for example locking of the reduction gear or autorotation of the fan wheel (commonly referred to as windmilling). In fact as the HP body and the LP body are decoupled, it is possible for the LP body and the fan to turn while the rotational speed of the HP body is uncertain.
In the current technology, the reduction gear is lubricated by a lubrication unit actuated by an accessory gear box (AGB) which is generally mounted in the nacelle compartment of the propulsion assembly. This accessory gear box comprises power take-off means on the engine of the turbine engine, by means of a radial shaft which is coupled to the HP body. In the event of windmilling, the HP body does not turn and the lubrication unit is not active whilst the plain bearings of the reduction gear must always be lubricated.
Therefore, there is a need for pumping the oil for lubrication of the reduction gear, in particular when the engine is stopped. In order to meet this need, it has already been proposed to equip the turbine engine with a standby pump for lubricating the reduction gear in such a way that the reduction gear can still be lubricated, even when the HP body is stopped. In this case, it is necessary to add a power take-off on the fan or a power supply circuit in order to actuate this pump. It can also raise problems of overall size, of mass and of service life. Thus the introduction of this pump has the drawback that it complicates the architecture of the engine and contradicts the desired objective of compactness and weight reduction.
The present disclosure provides a simple, effective and economical solution to at least some of the problems of the prior art.